Matched by chemical composition and mechanical properties, not a formal equivalence claim. Always verify against the applicable standard before substitution.
Chemical Composition (%)
C
Mn
Cr
Mo
Ni
0.12-0.18
0.25-0.50
1.00-1.40
0.15-0.30
3.90-4.30
More data from BS 970 (Part 1):1991
From the standard
Other composition limits
Category
Category 1 steel
Category 1 steels are preferred for new designs and established designs (clauses 1.4 and 2.1). Category 2 steels are printed in italic type.
Source: BS 970 (Part 1):1991, Table 7
Maximum hardness by condition of delivery
Bars and billets for forging, max
277 HB
Forgings and bars for machining, sub-critically annealed, max
277 HB
Forgings and bars for machining, normalized and tempered, max
269 HB
Maximum Brinell hardness when specified on the order, in the condition of delivery (Table 9).
Source: BS 970 (Part 1):1991, Table 9
Hardenability, end quench testHardness band
Hardness band (HRC, minimum to maximum) by distance from the quenched end (mm)
1.5
3
5
7
9
11
13
15
20
25
30
35
40
45
Distance from quenched end (mm)
1.5
3
5
7
9
11
13
15
20
25
30
35
40
45
Maximum, HRC
45
45
45
45
45
45
45
45
45
45
44
44
44
43
Minimum, HRC
38
38
38
38
38
38
38
38
37
36
35
34
33
32
H grade requirement for case hardening steels; see also the curves in Appendix A, which are for guidance only.
Source: BS 970 (Part 1):1991, Table 7
Heat treatment
Preheat treatment temperature, hardenability test
880-900 deg C
Austenitizing temperature, hardenability test
830 deg C
Table 9: heat treatment of case hardening steels. Values as printed; a dash in the table means not specified.
Source: BS 970 (Part 1):1991, Table 9
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